Fuse plug



March 5, 1935. M GOLDMAN- 1,993,403

FUSE PLUG Filed Aug. 27, 19152 Patented Mar. 5, 1935 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to fuse plugs and more particularly to electric fuses which are adapted to be threaded into the standard socket and which are provided with a fusible member of metal which will melt and interrupt the electric circuit when an overload current passes therethrough.

It is sometimes difficult to examine a fuse and determine whether or not the fuse has blown out or whether it is in good condition, notwithstanding the fact that practically all such fuses are provided with a transparent portion or window through which the fusible member may be seen. Notwithstanding this fact, the inside of the fuse is more or less dark, and as the fusible member or blade itself is not of a sufliciently light or contrasting color, it is difficult to determine its condition.

Difficulty has also been experienced in manufacturing and assembling the parts of such a fuse economically, and, at the same time, so make and assemble the parts that they will be held securely and firmly in position and there will be no danger of their becoming loose in the handling of the fuse or inserting it in place.

One object of the invention is the provision of a fuse plug which may be economically manufactured and assembled in a secure and satisfactory manner so that the parts will not become loose.

Another object of the invention is the provision of a fuse which may be economically manufactured and which will, at the same time, provide for a clear view of the fusible member or blade so that its condition may be readily determined.

A still further object of the invention is the provision of a fuse plug the parts of which may be so assembled and secured together that there will be no danger of these parts becoming loose during the handling of the fuse.

A still further object of the invention is to provide a fuse with a transparent or window portion which will have a magnifying effect so that the condition of the fusible member viewed through this window may be readily determined.

Still another object of the invention is the provision adjacent the fusible member of a member of a contrasting color so that the fuse will stand out in a prominent manner and may be seen distinctly.

To these and other ends the invention consists in the novel features and. combinations of parts to be hereinafter described and claimed.

In the accompanying drawing:

Fig. 1 is a side elevational view of a fuse embodying my improvements;

Fig. 2 is a top plan view of the same;

Fig. 3 is a sectional View on line 3-3 of Fig. 1;

Fig. 4 is a sectional view on line 44 of Fig. 3;

Fig. 5 is a perspective View of the base member of the fuse;

Fig. 6 is an enlarged view similar to Fig. 2; and

Fig. 7 is a top plan View of a fuse of slightly modified form.

To illustrate a preferred embodiment of my invention I have shown in Figs. 1 to 6 of the drawing a fuse plug having a body portion 10 and a base portion 11. The body portion is made of an insulating material, preferably glass in this instance, so as to provide a transparent or window portion 12 through which a view of the interior of the fuse may be had. The body 10 consists of a top portion and a hollow cylindrical sleeve depending therefrom, the sleeve being provided with threads 13 upon the exterior thereof. The under side of the top of the fuse below the portion 12 is convex in form, as shown at 14, so as to afford a magnifying effect and at the same time leave the upper surface of this member substantially flat.

Within the cylindrical body portion of the member 10 are provided oppositely disposed lugs 15 and 16 presenting shoulders 17 and 18 which extend longitudinally ofthe hollow interior portion of this member. The shoulders 17 and 18 present laterally directed stops for a purpose to be described hereinafter.

The base 11 of the fuse is provided with a substantially circular flange portion 19 of about the same diameter as the cylindrical portion of the top member 10 and designed to abut the lower edge of this member. Above the member 19 the base portion of the fuse is provided with a sleeve 20 of substantially semi-cylindrical form, the sleeve being hollow so that shoulders 21 and 22 are provided at the opposite edges. A groove or recess 23 extends across the top of the sleeve 20 downwardly upon the exterior surface thereof and across the top of the flange 19.

A contact member 24 is provided at the lower end of the base 11 and electrically connected thereto is the fusible member or blade 25 which, as clearly shown in Fig. 3, extends upwardly therefrom and is folded laterally upon itself so as to present a portion extending below the window or transparent portion 12 of the top. This part of the fuse is provided with a restricted portion 26 of greater electrical resistance than the remainder, so that it will be caused to melt when an excessive current is passed therethrough. The other end of the fusible member is disposed in the groove 23 and extends downwardly along the outside of the sleeve 20, outwardly through the groove in the flange 19, and thence upwardly within a groove 2'? provided exteriorly upon the cylindrical threaded portion of the top- 10.

A threaded metal shell 28 having a flange 29 to underlie the flange 19 is threaded upon the cylindrical portion of the member 10 to hold the parts 10 and 11 together. It will be understood that the flange 29 is provided with a central opening through which the base member 11 extends. The end of the fusible member within the groove 27 extends to a point adjacent the upper edge of the metal shell 27, and the fusible member and shell may there be secured together by means of a drop of solder or the like 30, so that the fusible member is secured to the shell as well as being electrically connected thereto, and is also electrically connected to the metallic contact member 24.

It will be understood that when the cylindrical portion 20 of the base member is inserted within the cylindrical portion of the member 10, the shoulders 21 and 22 will abut the shoulders 17 and 18 formed interiorly upon the member 10 so as to position the base member and prevent any rotative movement between the members 10 and 11. The metal shell 28 is then screwed into place and the solder 30 applied. This will prevent the unscrewing of the metal shell 27 so that the parts will be held firmly together with substantially no play therebetween.

It will also be apparent that the restricted portion 26 of the fusible member may be viewed through the magnifying window portion 12 of the member 10. As, however, the inside of the fuse may be more or less dark and the restricted portion of the fusible member will not present a distinct contrast with respect to the remaining parts of the fuse, I find it desirable to place a disk 31 of insulating material below the restricted portion 26 of the fusible member and between it and the adjacent lower folded portion of this member. The member 31 may be of paper or fibre or the like and is preferably brightly colored upon its upper surface. It is of such a size that it will lie below the transparent portion 12 so that when the fuse is viewed through this portion only the disk 31 and the part of the fusible member which lies above it will be seen. If desired, indieia may be placed upon the upper surface of the member 31 to designate the capacity of the fusible member.

It will be apparent that the base 11, flange l9 and sleeve 20 are integrally formed of an insulating material and the upstanding portion of the sleeve 20 will lie between the upwardly and downwardly extending runs of the fusible member and will by its engagement with the downwardly extending run of this member hold it securely in position.

In Fig. 7 of the drawing, I have shown a slightly modified form of fuse wherein a disk of insulating material 31 similar to the member 31 is placed above the upper fold of the fusible member instead of below it, and is provided with a cut-out portion or opening 32 through which the restricted portion 26 of the fusible member is exposed to view. Otherwise the fuse shown in Fig. 7 is like that shown in Figs. 1 to 6 of the drawing.

While I have shown and described some preferred embodiments of my invention, it is to be understood that the same are not to be limited to all the details shown, but are capable of modification and variation within the spirit of the invention and the scope of the appended claims.

What I claim is:

l. A fuse plug comprising a hollow body, a base, and a shell threaded upon the hollow body and engaging the base to secure the parts together, said base having an upstanding hollow portion within the hollow body, said. portion being substantially .semi-cylindricalin shape at its upper end, the exterior portion of said hollow body and the upstanding portion of said base being provided with registering and communieating grooves, a fusible member within the hollow body having a portion thereof extending downwardly through the groove in the base, outwardly between the body and the base, and upwardly in the groove in the body and there secured to the upper edge of said shell, and integrally formed means upon the opposite walls of the body to abut the faces of the semi-cylindrical portion of the base to prevent relative rotation of these parts and insure registration of said grooves 2. A fuse plug comprising a. hollow body, a base, and a shell threaded upon the hollow body and engaging the base to secure the parts together, said base having an upstanding hollow portion within the body, the upper end of this portion being semi-cylindrical in shape, the exterior portion of said hollow body and the upstanding portion of the base being provided with registering and communicating grooves, a fusible member within the hollow body having a portion thereof extending over the top thereof and downwardly through the groove in the base, outwardly between the body and base, and upwardly in the groove in the body, and there secured to the upper edge of the shell, and laterally directed shoulders upon opposite walls of the body to abut the faces of the semi-cylindrical portion of the base and prevent relative rotation of the parts.

3. A fuse plug comprising a hollow body and a base, said body being of substantially cylindrical form and open at its lower end, said base having a flange to abut the lower end of the body and an upstanding hollow portion to be received within the body, said portion being substantially semicylindrical in shape at its upper end, a shell threaded upon the body and engaging the flange on the base, the upstanding portion of said base and the upper side of said flange being provided with a continuous groove, a fusible member within the hollow body and having a portion extending through said groove between the base and body, said body being provided with an exterior longitudinally extending groove communicating with the groove on the upper side of the flange, the end of said fusible member extending upwardly in said groove and being secured to the upper end of the shell, and laterally directed shoulders integrally formed on opposite walls of the body to abut the faces of the semi-cylindrical portion of the base to insure assembly thereof, with the groove in the body in registration with that in the base and prevent relative rotation of the base and body.

MORRIS GOLDMAN. 

